Convertible ladders



Feb. 17, 1959 c. A. osovsKr Erm.

CONVERTIBLE LADDERS 2 Sheets-Sheet 1 Filed June 30, 1958 M M w rbd.

MAL@ fue/ ATTORNEY Feb. 17, 1959 c. A. osovsKl ETAL 2,873,903

CONVERTIBLE LADDERS Filed June 3o, 1958 2 sheets-sheer 2 INVENTOR s A e/'rATToRNEY 'CONVERTIBLE LADDERS Conrad A. Osovski and Raymond H. Shaver, Newark Valley, N. Y., assignors to 'Chesehro Whitman Mannfacturing Corporation, Newark Valley, N. Y., a corporation of New York Application June 30, 1958, Serial No. 745,615

16 Claims. (Cl. 228-25) The present invention relates to ladders, and more particularly to a convertible ladder of the type which may be utilized as a step ladder either on horizontal or uneven ground, and which may be converted into an extension ladder.

An important object of the invention is to provide a ladder which is of simple construction, easy to manipulate, and safe in operation either as an extension ladder or as a step ladder.

Another object of the invention is to provide a device of the above character which may be assembled by utilizing component parts of known construction.

An additional object of the invention is to provide a multipurpose ladder of the above described character which, in addition to being capable of use as an extension or step ladder, may be further adjusted for use as a step ladder on uneven or stepped ground.

A further object of the invention is to provide a ladder of the above described character which consists of relatively few component parts, and which may be collapsed into a relatively small and compact package for transport and storage.

A concomitant object of the instant invention is to provide a multi-purpose ladder one part of which is longitudinally adjustable when used as a step ladder, and which is Yof adjustable overall length when used as an extension ladder. Y l

The above and many other objects of our invention are attained by the provision of a ladder comprising two relatively movable sections so connected with each other that one thereof is slidable with respect to the other in upward and downward directions; of Ameans forming part of one of said sections for retaining the two sections in a selected position when they are inclined with respect to each other; and means for locking the sections to each other when the sections are in substantially parallel planes but displaced with respect to each other.

More particularly, the novel assembly comprises two relatively movable sections one of which constitutes what is generally known in step ladders as the front section, while the other section may be of similar design and may constitute the so-called back support. All locking, guiding, retaining and spreading means forming part of the improved convertible ladder are preferably carried and/ kor formed by one of the sections while the rails of the other section, save for the connecting elements therebetween which perform an irriportant.r function in ther practice of this invention, are unobstructed to permit unimpeded displacements thereof with respect to the first mentioned stationary section.

The guide means for leading the movable section with respect to the stationary section comprises a bracket, preferably of U-shape, connected with the spreader means in such a way that, though the movable section is free 4to pivot or be longitudinally displaced with respect to the stationary section when the locking assemblies are not in engagement, with a selected connecting4 element, said movable section is held in a selected position against further upward displacement with respect to the stationaryl section when the locking means forming part of the `stationary section is in engagement with a selected vconnecting element. Each spreader is pivotally connected to the stationary section and is, further connected with the bracket of the guide means which latter, too, is carried by the stationary section. The connection between the spreaders and the bracket preferably comprises a pair of culi-shaped guiding and retaining elements defining passages for the rails of the movable section, and rigid connecting means between said retaining elements and the bracket. The latter is connected to the stationary section at a point close to the upper end thereof and the retaining elements or cuffs are downwardly spaced therefrom so that the two sections are also prevented from pivotal displacements with respect to each other by the spreaders and by being in engagement at a point close to the upper ends of rails which form part of the stationary section when the novel device is used as a step ladder.

An important feature of the present invention is in that the locking means for preventing upward displacements of the movable section is integral with and formed by the stationary section in that the latters rails are provided with two seats or cutouts adjacent to their upper ends, the seats being horizontally aligned and being of such shape and size to receive therein a selected connecting element of the movable section when the ladder is used as a step ladder on horizontal or uneven ground. When the spreaders are in operative position, they together with the guide bracket prevent removal of a connecting element from its seats in the rails of the stationary section. When the spreaders are collapsed, the movable section may be brought into parallelism with and is then slidable relative to the stationary section to allow for conversion of the novel device into an extension ladder.

The other locking assembly for preventing downward displacements of the movable section when the device of our invention is used as an extension ladder comprises one or more retaining and supporting members, for eX- ample, hooks or bails iixed to the stationary section to receive a connecting element of the movable section and to firmly hold it against pivoting or other movements with respect to the stationary section, save for upward displacement which is necessary to allow for conversion of the device back into a step ladder, if desired. The bail or bails are preferably pivotally mounted on the rails of stationary part in such a way as to rest against and be fully supported by a step or by the rails of the stationary section when a connecting element of the movable section is received therein. Thus, the stresses are shared by a selected step or by the rails of the stationary section, the latter also preventing pivoting of the bail or -bails under-the weight of the movable section supported thereby.

According to a preferred embodiment of our invention, the width of back support exceeds the width of the front section so that the upper ends of front rails are received between the rails of the back support and the connecting elements need not extend beyond the rails of the back support as they areat all times in a position to be received in the seats or sockets provided at the upper ends of frontrails.

in a modification of the just described embodiment, the connecting elements extend beyond the rails of the back support and the distance between the rails of the back support is less than the distance between the rails of the front section. The portions of connecting elements extending beyond the back rails are receivable in the seats provided in the front rails when the novel device is used as a step ladder. In this embodimenn, the guide elements and certain parts, of the spreading means 3 require some modification in order to allow unimpeded travel of the back support with respect to the front section.

Other features, advantages and attributes of the novel ladder will become `apparent and will be pointed out in greater detail in the course of the following detailed description of certain embodiments selected for illustration in the accompanying drawings wherein Fig. 1 is side elevational view of one embodiment of the improved device showing in full lines relative positions of the stationary front section and of the movable back support when used as a step ladder on horizontal ground, in dot-dash linesthe position of back support when the step ladder is used on stairs, and in broken lines the position of back support when the assembly isutilized as an extension ladder;

Fig. 2 is an enlarged fragmentary View of the ladder as seen from line 2-2 of Fig. 1 in the direction of ar rows;

, Fig. 3 is an enlarged fragmentary view of the upper end portion of Fig. l;

' Fig. 4 is perspective view of a modified locking and retaining device against downward displacement and pivoting movements of the back support; l

l Fig. 5 is perspective view of another embodiment showling the upper part of a ladder in which the rungs extend `beyond the rails of back support; and

Fig. 6 is a top plan view of the ladder shown in Fig. 5. Referring now in greater detail to Figs. 1 to 3, the convertible ladder therein shown comprises a front-section l 10 and a second section or back support 11. The front section includes two spaced rails 12, 13 with a plurality of preferably uniformly spaced steps 14 therebetween. The top step 15 at the upper end of front section 10 is somewhat larger than the steps 14 therebelow and is at least partly covered with a layer 16 of sheet metal 0r Vthe like. Immediately adjacent to the top step 15, front rails 12, 13 are formed with substantially semicircular cutouts or seats 17, the walls surrounding these seats being reinforced by extending the sheet metal layer 16 thereover. It will be noted that the seats 17 are provided in the end faces 12a, 13a of the respective front rails so as to face the connecting rungs of the back support 11, these rungs extending between and connecting rear rails 18, 19. Asbest shown in Fig. 2, the distance between the upper ends of front rails 12, 13 is less than the distance between parallel rear rails 18, 19 Whereby, in the position of Fig. l, a selected rung 20 may be received in the seats 17 of said front rails.

`The connection between front section 10 and Second section or back support 11 comprises a two-piece bracket assembly 21, 22 fastened to front rails 12, 13, respectively, and so formed as to guide the back support when the latter is in its broken-line position 11 or to determine the extent to which the back support may be pivoted with respect to the front section, that is, when the back support is in its full-line or dot-dashlne position 11, 11, respectively. Rails 1S, 19 of the back support are further guided by cuff-shaped retaining elements 23 each connected to one of brackets 21, 22 by means of braces 24 and with one of front rails 12 13 by means of spreader assemblies 25. Thus, and as shown in Fig. l, rear rail 18 is guided by a cuff 23 and by the bracket member 21, and may be held in inclined position with respect to `front rails 12, 13 by an expanded spreader 25. The other rear rail 19 is connected in identical manner with bracket member 22 and front rail 13, respectively. When the spreaders 25 are collapsed into their broken-line positions 25', back support 11 may be pivoted labout the upper inner edges 21a, 22a of respective bracket members 21, 22 into the position 11', and the uppermost rung 20u is thereby caused to move out of its seats 17 in front rails 12, 13 to permit movements of back support 11 in a plane substantially parallel with the plane of front sec- "das-ravens; y

tion`10, i. e. into the position 11. A selected rung 20v 16 may then be received in a bail 26 attached to the respective front rails 12, 13, this bail being of such shape and being so mounted on the front section 10 that it prevents downwardly directed as well as pivoting movements of back support 11 with respect to the front section 10. When the back-support is so retained in the positionll, the novel assembly may be used as an extension ladder. v

To recouvert the device into a step ladder, an operator merely lifts rung 20v from the bail 26 and pivotsV the back support about the-edges 21a, 22a of brackets 21, 22 while the spreaders 25 return into the full-line -expanded position. seats 17; for example, when the ladder is to be used on stairs 27, the nextftovthefupperrung 20w may be received in said seats, the'upper end of back support 11 and the uppermost rung 20u being then in the position 11", 20u", respectively. Rung 20w then occupies the position previously held by rung 20u, as indicated by reference numeralzou". It will be noted that the lower ends of rails 12, 13 and 1S, 19 are provided with customary antiskid rubber feet 28.

As is best shownin Fig. 3, each substantially semicircular seat 17 is preferably bounded by a horizontal surface 17a.which is theundersurface of top step 15, this surface preventing unintentional removal of a selected rung 20 from seats 17 when the novel device is used as a step'ladder. Since the distance between the rear rails 1S, 19 exceeds `the length of topstep 15 (see Fig. 2), back support11-is freelyA slidable with respect to the l-ifront section'10 whenthe spreaders 2S are collapsed. As before mentioned, cuis 23 at all times guide the back rails 18, A-19 in directions to move the back support into position 11' or 11", depending upon the intended use of the ladder. It V,will be noted that the bracket members 21, 22 are olfset, as at 21b, 22h, which is necessary since the width of back support 11 at that point exceeds the width offront section 10. Similar offset zones 25a are provided in one member of each spreader 25.

Fig. 4 illustrates in greater detail the bail 26 which, as above explained, prevents pivoting and downward movements of back support 11 when the novel device is used as an extension ladder. The bail consists of a single piece of suitably bent steel wire which is fulcrumed in a pair of bearing plates 29, each plate being carried by one of front rails 12, 13. Bail 26 comprises apair of substantially L-shaped end portions 26a, 26b whose shorter legs abut against the respective front rails 12, 13 to prevent further pivoting of the bail when the latter is in a position to -receive a selected connecting rung 20. In Fig. 4, member 26 is shown in such operative position ready for reception of a rung 20 on its portions 26e, 26d, the portions 26e, 263c preventing pivoting movements of a so supported rung. When the bail is not in use, it may be pivoted into the space between front vrails 12, 13, i. e. into the position 26 shown in Fig. l, in order to allow unimpeded displacements of back support 11 in a plane substantially parallel with the plane of front section 10 (see the position 11 of back support in Fig. l). When the bail 26 is so pivoted, its end portions 26a, 26h abut against the end surfaces of respective front rails 12, 13 at a point below the bearing plates 29.

A somewhat different embodiment of our improved ladder is shown in Figs. 5 and 6. The main difference is in that the distance between rear Vrails 118, 119 is less than the distance between the upper ends of front rails 112, 113 andvthat, in order to be received in seats 117 of the front rails, rungs 120 must extend beyond the rear rails. Extensions 120e of the rungs also render necessary certain modifications of guide bracket 121 and of cuffs 123 since these parts mustpermit unimpeded sliding movements of the back support 111 with respect to the frontA part 110. As may be observed in Fig. 6, theoiset zones in-bracket .121 are not necessary,'the

Any selected rung may be received in latter being of U-shape and having its upper inner edge 121:1 at such distance from the front rails 112, 113 that this edge guides back rails 118, 119 `in their sliding movements with respect to the front section 110. Each cuff 123 has a U-shaped offset portion 12351 permitting the passage of projecting ends or extensions 12de of rungs 120 therethrough. Spreaders 125 and links or braces -124 are connected to U-shaped portions 123m and to front rails 112, 113 and bracket 121, respectively. The upper ends of rails 112, 113 are coated with a reinforcing layer 116 of sheet metal or the like, layers 116 also coating the surfaces surrounding the seats 117.

The operation of this ladder is analogous to that of the device described in connection with Figs. l to 3. A certain amount of customary hardware, such as blocks, tensioning rods and washers, is shown in Figs. l and 4. These parts are well known in the art of making ladders and hence require no detailed description. Reference is also had to our copending application Serial No. 737,629, filed May 26, 1958, as regards various modifications of the bail 26 which may be replaced by two spaced hooks or a unitary member-of slightly different construction.

Some changes may be made in the construction and arrangement of the parts of our device without departing from the real spirit and nature of the invention, and it is our intention to cover by the appended claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.l

What we claim and desire to protect by Letters Patent is:

l. A convertible ladder comprising, in combination: a first section having an upper end and seats provided therein adjacent to said upper end; a second section having a plurality of spaced connecting elements each receivable in said seats; means connected with said first section for so guiding said second section that the latter is free to perform angular movements with respect to said first section and sliding movements in directions toward and away from the upper end of said lirst section; means connected with said last mentioned means and with said first section for limiting the angular movements of the second section with respect to said rst section; and means connected with said first section and engageable with a selected connecting element for holding the second section against sliding movements away from the upper end of said first section.

2. A convertible ladder comprising, in combination: a rst section having a pair of spaced rails and steps therebetween, each of said ,rails having an upper end and a seat adjacent to said upper end; a second section having a pair of parallel spaced rails and a pluralityv of parallel connecting elements therebetween, each of said connecting elements being receivable in the seats of said first mentioned rails; guide means connected with the rails of said iirst section and engaging with the rails of said second section in such manner as to permit sliding movements of said second section toward and away from the upper ends of said first mentioned rails and pivoting movements of said second section between positions of substantial parallelism with and of inclination with respect to said first section; means connected with said guide means and with said first section, respectively, for limiting the extent of inclination of the second section with respect to said first section; and means connected with said first section and engageable with a selected connecting element for retaining said second section in a position of parallelism with and against sliding movements in a direction away from the upper ends of said lirst mentioned rails.

3. A convertible ladder comprising, in combination: a first section having a pair of spaced rails and a plurality of steps therebetween, each of said rails having an upper end and a seat located in the proximity of said upper end thereof, said seats being horizontally aligned;

a second section having a pair of parallel spaced rails and a plurality of parallel connecting elements therebetween, the distance between the rails of said second sec-- tion being greater than the distance between the rails of said rst section adjacent to the upper ends thereotc whereby a selected connecting` element is receivable in the seats of said first mentioned rails; guide means connected with the rails of said iirst section in the proximity of said seats and engaging with the rails of said second section in such manner that the second section is slidable with respect to said rst section in directions toward and away from the upper ends of said first mentioned rails, and is pivotable between a position of substantial parallelism with and of inclination with respect to said iirst section; spreader means connected with said guide means and with said first section for controlling the extent of inclination of the second section with respect to said first section; and locking means connected-with said first section beneath said guide means and adapted to en gage with a selected connecting element when the second section is in substantial parallelism with said first section for holding the second section against sliding movements in a direction away from the upper ends of said first mentioned rails and against pivoting movements with respect to said first section.

4. The combination as set forth in claim 3, wherein said locking means consists of a bail pivotally fixed to said irst mentioned rails for movements between a first position in which it is adapted to engage with a selected connecting element and a second position in which it allows sliding movements of the second section with respect to said lirst section while the latter is substantially parallel with said second section.

5. The combination as set forth in claim 4, wherein said bail has at least one projecting portion engaging with said first mentioned rails and holding the bail against further pivotal movements when the latter is in one of said positions.

6. The combination as set forth in claim 3, wherein said guide means comprises a pair of brackets each fixed to one of said first mentioned rails with said brackets defining a passage for said second section, a pair of cuil' shaped elements each connected with one rail of said second portion, and a pair of links each articulately connected with one of said brackets and with one of said cuff shaped elements.

7. The combination as set forth in claim 6, wherein said spreader means comprises a pair of collapsible members each having one end pivotally connected to one of said iirst mentioned rails and another end pivotaily connected to one of said cuff shaped elements.

S. The combination as set forth in claim 3, wherein each of said first mentioned rails has a relatively narrow end surface facing said second section and said seats are provided in said end surfaces.

9. The combination as set forth in claim 8, wherein said connecting elements are rungs of substantially circular cross sectional contour and said seats are of substantially semicircular shape.

10. The combination as set forth in claim 8, further comprising reinforcing means applied to each of said iirst mentioned rails and coating the walls surrounding said seats.

l1. The combination as set forth in claim 8, further comprising a top step connected to the upper ends of said first mentioned rails and having an upper surface greater than the upper surfaces of said first mentioned steps.

l2. A convertible ladder comprising, in combination: a first section having a pair of spaced elongated rails and a plurality of steps therebetween, each of said rails having an end and a seat located in the proximity of said end thereof, said seats being aligned transversely to the longitudinal direction of said rails; a second section having a pair of spaced elongated parallel rails and a plurality of transverse parallel connecting elements therebetween, the distance between said last mentioned rails being less than the distance between said seats and each of said connecting elements having two portions each extending through and beyond one of said last mentioned rails to be receivable in one of said seats; guide means connected with the rails of said rst section in the proximity of said seats and engaging with the rails of said second section in such manner that the latter is slidable toward and away from the ends of said rst mentioned rails and is pivotable between a position of substantial parallelism with and a position of inclination with respect to said rst section; spreader means connected `with said guide means and with said first section for controlling the extent of inclination of the second section with respect to said rst section; and locking means connected with said rst section at a point spaced from said seats and adapted to engage with a selected connecting element when the second section is substantially parallel with said first section for holding the second section against sliding movements in a direction away from the ends of said iirst mentioned rails and against pivoting movements with respect to said iirst section.

13. The combination as set forth in claim 12, wherein said guide means comprises a substantially U-shaped bracket having a pair of legs each connected with one of said first mentioned rails and a base defining with said legs a passage for said second section, a pair of cui shaped elements each slidably receiving one rail of said second section, each of said cuff shaped elements hav- 30 ing an offset portion for permitting the passage of a portion of one of said connecting elements therethrough, and a pair of connecting links each pivotally connected to one leg of said bracket and to one of said cut shaped elements, respectively.

14. The combination as set forth-in claim 13, wherein said spreader means comprises a pair of collapsible members each having an end articulately connected to one of said first mentioned rails and another end articulately connected with one of said cuff shaped elements.

15. The combination as set forth in claim 12, wherein each of said rst mentioned rails has a relatively narrow end surface and said seats are provided in said end surfaces,

16. The combination as set forth in claim 15, wherein said seats are of substantially semicircular contour and the projections of said connecting elements are of substantially circular cross sectional contour.

References Cited in the tile of this patent UNITED STATES PATENTS 725,377 Sturgeon Apr. 14, 1903 1,050,273 Hattenback e tal 1--- Jan. 14, 1913 1,837,187 Allen 1 Dec. 22, 1931 2,675,155 Bair Apr. 13, 1954 FOREIGN PATENTS 144,812 Switzerland Apr. l, 1931 

